How to start working for developing a virtual printer driver?

I am new to device driver development... I have studied some thing
about windows DDK...i want to develop a virtual printer driver.... The
first step is to convert it to EMF (Then finally to JPEG). I have been
subscribed to OSRONLINE also.. They said me to refer to GENPRINT
sample given in ..../Windows DDK../src/print/genprint sample.. I have
build it using WinXP checked build environment... It now generates a
GENPRINT.DLL... ("I haven't changed any of the source code") Now how
to run the sample? They say me write a INF and GPD file... Whether
this is needed or not? If it is needed, how to write a INF and GPD...
Which material to refer for a beginner? Do I need to change the source
code of genprint? Please help me.... Thank you for all your valuable